2.9. High variation threshold

For the sets of genes that were above the threshold of technical noise we calculated the coefficient of variation (CV) using the standard definition of ratio of the standard deviation to the mean, and divided them in four groups (quartiles) according to their CV. The High variation (High CV) genes were the ones that were falling in the fourth quartile of the CV. The rest of the genes were defined as Non High CV. Gene ontology enrichment was performed using DAVID (Dennis et al., 2003).